The present invention relates generally to wheelchairs and more particularly, to wheelchairs which are specially equipped for ascending or descending stairs or steep inclines.
It is well-known to provide a wheelchair with endless traction belts to aid in ascending and descending stairs and inclined surfaces, as well as traveling over level horizontal surfaces. It is well-known to provide motors for driving wheelchairs, particularly for driving the endless traction belts to ascend and descend stairs. Heretofore, numerous techniques have been employed to equip wheelchairs and the like to ascend and descend stairs. Some of these mechanisms are limited to ascending and descending curbs or single steps at a time.
It has been suggested to equip a chair with a combination of endless traction belts in front, beneath and in back of the chair so that the chair rides at all times on one or more of the belts and when the operator is ascending or descending stairs, the front or rear belts, respectively, are used. Other mechanisms which are particularly suited for climbing and descending curbs employ levers to raise and/or lower the front of the chair to climb or descend a curb. Yet another type of mechanism provides the large side wheels of the chair constructed of a multitude of segments which fold so that these wheels can change shape to accomodate stairs.
These and other mechanisms provided in the past to enable the operator of a wheelchair to ascend and descend stairs generally support the chair and operator in the conventional upright position and do not lower the center of gravity of the operator and the chair with reference to the stair tread directly beneath the center of gravity. Hence, the hazards suffered by the operator if the chair should slip or fall over while climbing or descending stairs are considerably greater than would be encountered on a level surface. Furthermore, none of these mechanisms are so designed that the operator can easily reach the stair treads in back of or alongside the wheelchair while ascending or descending the stairs to remove any objects that may be in the way.